In a lot of modern music the bass tends to line up rhythmically with the drums, specifically the kick. There’s often more notes happening, but the bass will emphasize the kick hits, or at least the downbeat or backbeat if there’s a lot of kick or fills. It basically locks in the bass and drums as rhythmic elements, with the drums (again, specifically the kick) providing the ‘beat’ and the bass emphasizing that beat to make it hit harder. It’s why you see the bass player turned around nodding to the drummer in a lot of live acts - they’re making sure they’re locked in on the beat while the rest of the band does whatever it is they do to get chicks.
It’s also worth noting that for the most part, the bass is the bridge between the beat and the melodic content. The bass does double duty in locking in the beat and emphasizing the fundamentals of the melody. So it’s a balance of where the notes fall (the rhythm) and the notes being played (the melody). To make a good bassline, you really need both.
A pretty simple exercise is to grab a couple of your favorite tracks and EQ out everything above, say, 2k. Just listen to the bottom end and how the bass and drums interact.